Abstract

In this paper, we theoretically and experimentally study phononic band gaps and waveguiding for plate-mode acoustic waves in a square array of stepped cylinders coated on an aluminum thin plate. We show that the stepped cylinders shaped with a small segment of reduced diameter can change the phonon resonance frequencies and result in tailorable band gaps. We demonstrate the band-gap and waveguiding effects in the phononic plate utilizing finite-element method numerical calculations and pulse laser ultrasonic measurements. Experimental results agree well with the numerical predictions. The phononic band gaps, slow resonantacoustic waves, and waveguiding in the lower frequency range are experimentally observed. The results enable enhanced control over phononic metamaterial, which has applications in low-frequency guiding and isolation of acoustic waves, acoustic absorbers, and nondestructive evaluation.